The broad, long-term objective is to exploit a uniquely detailed data set to investigate the causes of fertility decline in Prussia from 1875 to 1910. The analysis examines in greater depth the issues raised by the Princeton European Fertility Project. The Prussian data cover a population in excess of 40 million (12.5 percent of all of Europe) and refer to geographical units some one-fifteenth the size of the European Fertility Project's. The analysis of Prussia includes not only much more detailed socioeconomic data, but also data which are geographically and temporally comparable. Therefore these data support a more appropriate test of fertility transition theory in general and allow a more appropriate test of the main conclusions reached by the European Fertility Project in particular. Our initial analysis suggests that analysis at a finer level of geographic detail reveals important within-region variation. The results of our pooled cross-section time series analysis generally support the economic theory of fertility decline and indicate that our model is a very powerful predictor of fertility decline. Funding for two years is requested to carry out the following steps: 1. Using 407 Kreise, our basic units of analysis, analyze variation in fertility levels, pace of fertility decline, and onset of fertility decline over time and across units utilizing analysis of variance techniques and mapping programs. Compare to larger units used in previous studies of the European Fertility Project. 2. Examine the impact of secularization on fertility decline using pooled cross-section time series methods. 3. Explore fertility level and decline by 28 occupations in each of 14 provinces of Prussia from 1882 to 1907. Examine fertility level and decline in 13 districts of the city of Berlin from 1875 to 1910. 4. Examine non-marital fertility decline using pooled cross-section time series methods. 5. Model the decline in infant mortality rate, legitimate and illegitimate separately, using pooled cross-section time series methods. 6. Test various hypotheses about the secular decline of demographic crises and general short-run variability of vital rates. For the full pooled sample we will examine how contextual variables reflecting these influences affect the sensitivity of short-run response of vital rates to food prices for marital fertility, non-marital fertility, and measures of nuptiality and mortality. We believe that this will be a more comprehensive test of fertility transition theory and associated infant mortality decline within the European context than has previously been possible. Lack of data for important variables combined with a lack of comparable data over time has often forced researchers to rely on simplistic cross-sectional analyses of European and LDC data, leading to possibly erroneous conclusions. We expect our research to shed more light on the mechanisms involved in the determinants of both historical and contemporary fertility and infant mortality decline.